CURLOPT_HSTSWRITEFUNCTION

Section: curl_easy_setopt options (3)
Updated: November 04, 2020
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NAME

CURLOPT_HSTSWRITEFUNCTION - write callback for HSTS hosts

SYNOPSIS

CURLSTScode hstswrite(CURL *easy, struct curl_hstsentry *sts,
struct curl_index *count, void *userp);

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTSWRITEFUNCTION, hstswrite);

EXPERIMENTAL

Warning: this feature is early code and is marked as experimental. It can only be enabled by explicitly telling configure with --enable-hsts. You are advised to not ship this in production before the experimental label is removed.

DESCRIPTION

Pass a pointer to your callback function, as the prototype shows above.

This callback function gets called by libcurl repeatedly to allow the application to store the in-memory HSTS cache when libcurl is about to discard it.

Set the userp argument with the CURLOPT_HSTSWRITEDATA(3) option or it will be NULL.

When the callback is invoked, the sts pointer points to a populated struct: Read the host name to 'name' (it is 'namelen' bytes long and null terminated. The 'includeSubDomains' field is non-zero if the entry matches subdomains. The 'expire' string is a date stamp null-terminated string using the syntax YYYYMMDD HH:MM:SS.

The callback should return CURLSTS_OK if it succeeded and is prepared to be called again (for another host) or CURLSTS_DONE if there's nothing more to do. It can also return CURLSTS_FAIL to signal error.

DEFAULT

NULL - no callback.

PROTOCOLS

This feature is only used for HTTP(S) transfer.

EXAMPLE

{
  /* set HSTS read callback */
  curl_easy_setopt(curl, CURLOPT_HSTSWRITEFUNCTION, hstswrite);

  /* pass in suitable argument to the callback */
  curl_easy_setopt(curl, CURLOPT_HSTSWRITEDATA, &hstspreload[0]);

  result = curl_easy_perform(curl);
}

AVAILABILITY

Added in 7.74.0

RETURN VALUE

This will return CURLE_OK.